There is a novella by J.P. Donleavy called The Lady Who Liked Clean Restrooms. It features a formerly wealthy Manhattanite whose husband left her for a younger woman. Reduced to near homelessness, she develops a true appreciation for that rare thing -- free, clean restrooms. How her penchant for cleanliness leads to an inheritance is the reward for our attention.
The Thin Woman: an Epicurean Mystery by Dorothy Cannell is a classic jolly good read. Featuring an overweight protagonist who stands to inherit money from her rich uncle IF she can lose the extra poundage, this title is one of "The 100 Favorite Mysteries of the Century" list created by Independent Mystery Booksellers Association.
John Grisham's The Testament presents a bunch of greedy would-be inheritors who are thrown into shock when their sure bet multibillionaire relative leaves his riches to a female missionary in Brazil. Nate O'Reilly, an alcoholic lawyer fresh from rehab, is sent to find the missionary. Lots of action and great characterization.
In The Codicil by Tom Topor, a millionaire leaves half his wealth to the secret daughter he fathered during the Vietnam War; much action and suspense follow.
The Widow's War by Sally Gunning is set in colonial Cape Cod. Whaling widow Lyddie Berry loses control of her life and home when a bully son-in-law violates her husband's will. This novel portrays the sexism of its era, and gives us a defiant heroine to root for.